Back in 2008, when Twitter had few users and even people in the technology sector were wary of its use, Boston venture capitalist Bijan Sabet
gave the fledgling social media company millions of dollars.

Already avid users of Twitter back then, Sabet and his colleagues at Spark Capital on Newbury Street seemed to grasp the potential of the 140-character communications tool when others dismissed it as a fad. Indeed, Sabet was one of the venture world’s early believers in social media, and now that faith has been rewarded with fortunes several times over.

Spark Capital has made several investments in Twitter over the years, a total of about $50 million, according to PrivCo, a New York firm that tracks venture capital. And when Twitter goes public later this year, those holdings could be worth $640 million — possibly much more — depending on the various estimates of Twitter’s overall market valuation.

That follows another big payoff for Spark, which made a potential profit of $180 million in May when another popular Internet tool it backed, blogging site Tumblr, was acquired by Yahoo Inc. for $1.1 billion.

“You’ve got to have guts, and they have that,” fellow venture capitalist Neeraj Agrawal
said of Spark’s investment in social media companies. “If there’s any question about social media being a fad, that’s behind us.”

Spark’s focus on riskier social media and consumer Internet businesses sets it slightly apart from other venture capital firms in the Boston area, many of which specialize in backing companies that make industrial strength software or hardware products for businesses. Though less glamourous, such enterprises often come with more predictable business models than Twitter, which has yet to make a profit.

At a venture capital conference in Nantucket earlier this year, Sabet said most investors in the Boston area tend to “have this bias to proven business models. . . . We tend to invest in things we use.”

Agrawal, a general partner at Waltham’s Battery Ventures, has invested alongside Spark in another local company, Wayfair LLC. Wayfair is an online retailer, not a social media company, but it has proven to be another huge business success, and if it goes public next year as expected, it should yield yet another big payday for its investors.

Another early investor in Twitter is Charles River Ventures, one of Boston’s more venerable venture firms. Its Twitter stake is smaller than Spark Capital’s.

Both Charles River Ventures and Spark Capital declined to comment.

Lucy McQuilken, a former investor at Intel Capital, recalls competing with Spark in 2008 to invest in game maker OMGPop Inc., which made the popular app Draw Something. Intel and other venture firms passed on making an investment, but Spark Capital doubled down. OMGPop was bought by Zynga for $180 million in 2012.

“Spark put more money in anyway, because they really believed in the space,” McQuilken said. “OMGPop was bought later for a very high return. I’ve seen Spark do that more than once. They are smart, not following the crowd.”

Sabet worked in Silicon Valley for a decade before joining Spark in 2005, bringing some of that relaxed West Coast attitude and style to the Boston firm, and a fondness for social media. A skilled amateur photographer, he often posts on Tumblr and the photosharing service Instagram. He had 41,812 followers on Twitter as of Friday.

“Bijan Sabet and his partners at Spark Capital made a big impression on us,” Twitter cofounder Biz Stone wrote back in 2008 when the venture firm first put up money in his company.

“Bijan has a strong sense of where Twitter is heading and sees our service as a new form of communication with the potential to have a real impact in the world.”

Sabet admits to being something of a fashion plate, albeit of the casual kind. The Boston Globe named Sabet among the most “stylish” Bostonians earlier this year, and he said his style was influenced by working in Silicon Valley for 10 years.

“I didn’t start my career on Wall Street. I don’t own cuff links,” he said.

Spark was not the first venture firm to invest in Twitter, but it got in early and repeatedly backed the company in later investing rounds. It is one of Twitter’s largest stockholders outside its core group of founders and employees. Among other influential investors joining Twitter in 2008 with Spark Capital was Amazon.com Inc. founder Jeff Bezos.

Sabet’s colleague, Spark cofounder Todd Dagres, is himself a veteran venture capitalist who previously worked for Battery Ventures, and earned a reputation in tech circles for being brash. Like other Boston venture capitalists in the 2000s, Dagres focused on computer and telecommunications hardware companies and related businesses, including backing Akamai Technologies Inc., the giant Internet traffic manager based in Cambridge.

And he got rich doing it. Dagres made some $53 million between 1999 and 2003, much of that investment profits on Battery Ventures companies, according to records in a tax dispute with the Internal Revenue Service.

Dagres used his money to start a new career, leaving Battery Ventures to finance films by independent directors.

After a few years he returned to the venture business, starting Spark Capital in 2005 with cofounders Santo Politi and Paul Conway, and focuses on Web start-ups, video game makers, and social media companies.

Spark has done well in sectors other than social media. It had a stake in Adap.tv, a video advertising platform, that AOL Inc. bought in August for $405 million, and Admeld, another advertising related company, that Google paid $391.2 million to acquire in 2011.

Earlier this year, Spark closed its fourth investment fund totaling $450 million, bringing the total amount raised in under a decade to $1.42 billion.

Another Spark-backed company in Boston is peerTransfer, which helps process tuition payments between international students and US schools.

PeerTransfer’s founder, Iker Marcaide, said Spark supported his company in 2010 when it was just him and a “horrible website.” Since then, with Spark’s help, it has grown to about 40 employees and raised $15 million in investments.

“They tend to bet on disruptive businesses across the board,” Marcaide said.

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